Funds are requested to purchase a circular dichroism spectrometer system. This system would consist of a Jasco J500a spectrometer, a computer and interface to control the machine as well as to store and manipulate the data, a stopped flow mixing device to study rapid reactions, a cryostat system for low temperature studies, and a magnetic CD attachment. There is currently only one functional circular dichroism spectrometer in the Atlanta area, an out-dated Cary 60 in the Emory University Department of Chemistry. This machine lacks the sensitivity, stability, and low-UV capabilities which are required in many of the studies described, and has required considerable repair to maintain it in working order. The proposed spectrometer system will be used in the research projects of three major users and five minor users. The research areas include: 1) role of protein conformation and protein-protein interactions in ubiquitin-dependent protein degradation, 2) studies on the mechanism of protein folding, 3) model studies on vitamin B-12 enzymes systems, 4) studies on the interaction of DNA with antitumor agents, 5) structure-function studies on complex flavoproteins containing covalently linked coenzymes or redox-active metal centers, 6) mechanistic and structural studies on enzymes of flavin metabolism, 7) the cytochrome P450scc-dependent metabolism of steroids, 8) the interaction of intercalating drugs with DNA, 9) magnetic CD studies on hydrogenase and sulfite reductase and 10) development of Fluorescence Detected Circular Dichroism techniques. These studies represent a broad range of important questions which can be best addressed with the proposed instrumentation. In addition, they define three general areas of overlapping interests among the research groups: the study of protein structure and function, the interaction of DNA with drugs and metals, and synthetic and model studies on biological catalysts.